COMPOSITION FOR PRIMING DENTAL AND BIOLOGICAL SUBSTRATES

COMPOSITIONS DE DECAPAGE DE SUBSTRATS DENTAIRES ET BIOLOGIQUES

English Abstract

Compositions and methods for priming or sealing dental or biological
substrates for subsequent bonding. The primer is particularly useful for
priming dentin of a tooth to prepare the dentin for bonding with a resinous
material. The primer comprises a mixture of a polymerization initiator such as
camphoroquinone and a polymerizable promoter such as methacrylic acid.
Polymerizable promoters within the scope of the present invention have at
least one ethylenically unsaturated group and at least one carboxylic acid
group. The primer may further comprise a solvent such as ethanol, a natural
resin such as Canadian balsam and a polymerizable resin such as 2-hydroxyethyl
methacrylate (HEMA). The primer can also be formed from a mixture of a
polymerization initiator, a natural resin and a polymerizable resin.

French Abstract

Compositions et procédés de décapage ou d'obturation de substrats dentaires ou biologiques pour application ultérieure d'un adhésif. L'agent de décapage est particulièrement utile pour le décapage de la dentine d'une dent, afin de préparer la dentine en vue de l'application par adhésion d'un matériau résineux. L'agent de décapage est constitué d'un mélange d'un initiateur de polymérisation tel que la camphoroquinone et d'un promoteur polymérisable tel que l'acide méthacrylique. Les promoteurs polymérisables considérés par la présente invention comportent au moins un radical éthyléniquement insaturé et au moins un radical acide carboxylique. L'agent de décapage peut comporter en outre un solvant tel que l'éthanol, une résine naturelle telle que le baume du Canada et une résine polymérisable telle que 2-hydroxyéthyl méthacrylate (HEMA). L'agent de décapage peut également être constitué d'un mélange d'initiateur de polymérisation, de résine naturelle et de résine polymérisable.

Claims

- 24 -
A stable premixed primer for sealing or priming for bonding a dental substrate or
a biological substrate, the stable premixed primer comprising:
a polymerization initiator: and
a polymerizable promoter characterized as being capable of being polymerized in
situ by initiation of the polymerization initiator after the primer is placed in contact with
the substrate, wherein the polymerizable promoter is selected from the group consisting
of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid,
ant wherein the polymerizable initiator and the polymerizable promoter once mixed
thereafter form a stable premixed primer ready for storage and subsequent application
directly to the substrate without additional mixing.
2. A primer as defined in claim 1, further comprising a polymerizable resin
3. A primer as defined in claim 1, further comprising a hydrophilic polymerizable
resin having at least one hydroxy group.
4. A primer as defined in claim 1, further comprising a hydrophobic polymerizable
alkyl resin.
5. A primer as defined in claim 1, wherein the polymerizable resin is selected from
the group consisting of a hydroxyalkyl methacrylate, a hydroxyalkyl acrylate, an alkyl
methacrylate. an alkyl acrylate, and mixtures thereof.
6. A primer as defined in claim 1, wherein the polymerizable resin is selected from
the group consisting of 2-hydroxyethyl methacrylate, bisphenol-A-glycidyl methacrylate, glycerol
dimethacrylate, methyl acrylate, triethyleneglycol dimethacrylate, and mixtures thereof.
7. A primer as defined in claim 1, wherein the polymerizable resin has at least one
phosphate group.

-25-
8. A primer as defined in claim 1, wherein the polymerizable resin has at least one
amine group.
9. A primer as defined in claim 1, further comprising a solvent.
10. A primer as defined in claim 1, further comprising a natural resin.
11. A primer as defined in claim 10, wherein the natural resin is derived from natural
sources and is selected from the group consisting of a rosin, distillate, a sap, an oil, a balsam,
a gum, and mixtures thereof.
12. A primer as defined in claim 10, wherein the natural resin is selected from the
group consisting of Canadian balsam, santarac, mastic, pontianak, copal, manilla, peruvian,
benzoin, elemi, opopanax, olibanum, styrax. benzoin siam, tolu, tall, pine, and mixtures thereof.
13. A primer for sealing or priming for bonding a dental or a biological substrate, the
primer comprising:
a polymerization initiator;
a natural resin; and
a polymerizable promoter characterized as being capable of being polymerized in
situ by initiation of the polymerization initiator after the primer is placed in contact with
the substrate, wherein the polymerizable promoter is selected from the group consisting
of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid,
and wherein the polymerizable initiator and the polymerizable promoter once mixed
thereafter form a stable premixed primer ready for storage and subsequent application
directly to the substrate without additional mixing.

-26-
14. A primer as defined in claim 13, wherein the polymerizable promoter has the
following formula
<IMG>
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an
unsaturated aliphatic radical, a halogen or a CN radical.
15. A primer as defined in claim 13, wherein the polymerizable promoter has the
following formula:
<IMG>
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an
unsaturated aliphatic radical, a halogen or a CN radical; and
wherein R1 is at least one oxygen atom, a saturated aliphatic radical, a saturated
aliphatic radical interrupted by at least one oxygen atom, an unsaturated aliphatic radical,
an unsaturated aliphatic radical interrupted by at least one oxygen atom, a homocyclic
radical, a heterocyclic radical, a polymerizable moiety, or an aryl radical having four to six
carbon atoms and valency of n+1 with n being an integer of at least 6.
16. A primer as defined in claim 13. wherein the polymerizable promoter is methacrylic
acid.
17. A primer as defined in claim 13, wherein the polymerizable promoter is selected
from the group consisting of 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic
acid.

-27-
18. A primer as defined in claim 13, wherein the natural resin is derived from natural
sources and is selected from the group consisting of a rosin, a distillate, a sap, an oil, a balsam,
a gum, and mixtures thereof.
19. A primer as defined in claim 13, wherein the natural resin is selected from the
group consisting of Canadian balsam, sandarac, mastic, pontianak, copal, manilla, peruvian,
benzoin, elemi, opopanax, olibanum, styrax, benzoin siam, tolu, tall, pine, and mixtures thereof.
20. A primer as defined in claim 13. further comprising a polymerizable resin.
21. A primer as defined in claim 13, further comprising a hydrophilic polymerizable
resin having at least one hydroxy group.
22. A primer as defined in claim 13, further comprising a hydrophobic polymerizable
alkyl resin.
23. A primer as defined in claim 13, further comprising a polymerizable resin selected
from the group consisting of a hydroxyalkyl methacrylate, a hydroxyalkyl acrylate, an alkyl
methacrylate, an alkyl acrylate. and mixtures thereof.
24. A primer as defined in claim 13, further comprising a polymerizable resin selected
from the group consisting of 2-hydroxyethyl methacrylate, bisphenol-A-glycidyl methacrylate,
glycerol dimethacrylate, methyl acrylate, triethyleneglycol dimethacrylate, and mixtures thereof.
25. A primer as defined in claim 13, further comprising a polymerizable resin having
at least one phosphate group.
26. A primer as defined in claim 13, further comprising a polymerizable resin having
at least one amine group.

-28-
21. A primer as defined in claim 13, further comprising a solvent.
28. A primer for sealing or priming for bonding a dental or a biological substrate, the
primer comprising:
a polymerization initiator;
a natural resin; and
a polymerizable resin.
29. A primer as defined in claim 28, wherein the natural resin is derived from natural
sources and is selected from the group consisting of a rosin. a distillate. a sap, an oil, a balsam,
a gum, and mixtures thereof.
30. A primer as defined in claim 28, wherein the natural resin is selected from the
group consisting of Canadian balsam, sandarac, mastic, pontianak, copal, manilla, peruvian,
benzoin, elemi, opopanax, olibanum, styrax, benzoin siam, tolu, tall, pine, and mixture
thereof.
31. A primer as defined in claim 28, wherein the polymerizable resin is hydrophilic and
has at least one hydroxy group.
32. A primer as defined in claim 28. wherein the polymerizable resin is a hydrophobic
polymerizable alkyl resin.
33. A primer as defined in claim 28, wherein the polymerizable resin is selected from
the group consisting of a hydroxyalkyl methacrylate, a hydroxyalkyl acrylate, an alkyl
methacrylate, an alkyl acrylate, and mixtures thereof.
34. A primer as defined in claim 28, wherein the polymerizable resin is selected from
the group consisting of 2-hydroxyethyl methacrylate, bisphenol-A-glycidyl methacrylate, glycerol
dimethacrylate, methyl acrylate, triethyleneglycol dimethacrylate, and mixtures thereof.

-29 -
35. A primer as defined in claim 28, wherein the polymerizable resin has at least one
phosphate group.
36. A stable premixed primer for sealing or priming for bonding a dental substrate or
a biological substrate, the stable premixed primer comprising:
a polymerization initiator;
a solvent; and
polymerizable promoter characterized as being capable of being polymerized in
situ by initiation of the polymerization initiator after the primer is placed in contact with
the substrate, wherein the polymerizable promoter is selected from the group consisting
of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid,
and wherein the polymerizable initiator, solvent and the polymerizable promoter once
mixed thereafter form a stable premixed primer ready for storage and subsequent
application directly to the substrate without additional mixing.
37. A primer as defined in claim 28, further comprising a polymerizable promotercharacterized as being capable of being polymerized in situ by initiation of the polymerization
initiator after the primer is placed in contact with the substrate, the polymerizable promoter
comprising at least one polymerizable prepolymer having at least one ethylenically unsaturated
group and at least one carboxylic acid group.
38. A primer as defined in claim 37, wherein the polymerizable promoter has the
following formula:
<IMG>
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an
unsaturated aliphatic radical, a halogen or a CN radical.

-30-
39. A primer as defined in claim 37, wherein the polymerizable promoter has the
following formula:
<IMG>
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an
unsaturated aliphatic radical, a halogen or a CN radical; and
wherein R1 is at least one oxygen atom, a saturated aliphatic radical, a saturated
aliphatic radical interrupted by at least one oxygen atom, an unsaturated aliphatic radical,
an unsaturated aliphatic radical interrupted by at least one oxygen atom, a homocyclic
radical, a heterocyclic radical, a polymerizable moiety, or an aryl radical having four to six
carbon atoms and a valency of n+1 with n being an integer of at least 6.
40. A primer as defined in claim 37, wherein the polymerizable promoter is methacrylic
acid.
41. A primer as defined in claim 37, wherein the polymerizable promoter is selected
from the group consisting of 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic
acid.
42. A primer as defined in claim 28, further comprising a solvent.
43. A primer for sealing or priming for bonding a dental or a biological substrate, the
primer comprising methacrylic acid, Canadian balsam, 2-hydroxyethyl methacrylate, ethanol and
camphoroquinone.
44. A primer for sealing or priming for bonding a dental or a biological substrate, the
primer comprising about 6% methacrylic acid by weight of the primer, about 15% Canadian
balsam by weight of the primer, about 53.3% 2-hydroxyethyl methacrylate by weight of the

-31-
primer, about 25% ethanol by weight of the primer and about 0.7% camphoroquinone by weight
of the primer.
45. A method for preparing a stable premixed primer for sealing or priming for
bonding a dental or a biological substrate, comprising the step of mixing a polymerization initiator
with a polymerizable promoter to form a stable premixed primer ready for storage and subsequent
application directly to a substrate without additional mixing, wherein the polymerizable promoter
is characterized as being capable of being polymerized in situ by initiation of the polymerization
initiator after the stable premixed primer is placed in contact with the substrate and wherein the
polymerizable promoter is selected from the group consisting of methacrylic acid, 4-pentenoic
acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid.
46. A method for preparing a primer for sealing or priming for bonding a dental or
biological substrate, comprising the step of mixing a polymerization initiator, a natural resin, and
a polymerization promoter to form a primer, wherein the polymerizable promoter is characterized
as being capable of being polymerized in situ by initiation of the polymerization initiator after the
primer is applied to the substrate and wherein the polymerizable promoter comprises at least one
polymerizable prepolymer having at least one ethylenically unsaturated group and at least one
carboxylic acid group.
47. A method for preparing primer for sealing or priming for bonding a dental orbiological substrate, comprising the step of mixing a natural resin, a polymerizable resin, and a
polymerization initiator.
48. A method for priming for bonding or sealing a dental or biological substrate with
a stable premixed primer comprising the steps of:
applying a stable premixed primer to the substrate, the stable premixed primer
comprising a polymerization initiator and a polymerizable promoter, wherein the
polymerizable promoter is characterized as being capable of being polymerized in situ by
initiation of the polymerization initiator after the stable premixed primer is applied to the

-32-
substrate. wherein the polymerizable promoter is selected from the group consisting of
methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid,
and wherein the premixed stable primer is characterized after being premixed as being
ready for storage and subsequent application directly to a substrate without additional
mixing; and
initiating the polymerization of the polymerizable promoter.
49. A method for priming for bonding or sealing a dental or biological substrate with
a primer comprising the steps of:
applying a primer to the substrate, the primer comprising a polymerization
initiator, a natural resin and polymerizable promoter, wherein the polymerizablepromoter is characterized as being capable of being polymerized in situ by initiation of the
polymerization initiator after the primer is applied to the substrate and wherein the
polymerizable promoter comprises at least one polymerizable prepolymer having at least
one ethylenically unsaturated group and at least one carboxylic acid group; and
initiating the polymerization of the polymerizable promoter.
50. A method for priming for bonding or sealing a dental or biological substrate with
a primer comprising the steps of:
applying a primer to the substrate, the primer comprising a natural resin, a
polymerizable resin, and a polymerization initiator; and
initiating the polymerization of the polymerizable promoter.
51. A kit for priming for bonding or sealing a dental or biological substrate with a
stable premixed primer comprising:
(a) a substrate conditioner; and
(b) a stable premixed primer comprising a polymerization initiator and a
polymerizable promoter, wherein the polymerizable promoter is characterized as being
capable of being polymerized in situ by initiation of the polymerization initiator after the
primer is applied to the substrate, wherein the polymerizable promoter is selected from the

32/1
group consisting of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and
2,2-dimethyl-4-pentenoic acid, and wherein the polymerizable initiator and the polymerizable promoter
once mixed thereafter form a stable premixed primer ready for storage and subsequent
application directly to the substrate without additional mixing.
52. A kit for priming for bonding or sealing a dental or biological substrate with a
primer comprising:
(a) a substrate conditioner; and
(b) a primer comprising a polymerization initiator, a natural resin and a
polymerizable promoter, wherein the polymerizable promoter is characterized as being
capable of being polymerized in situ by initiation of the polymerization initiator after the
primer is applied to the substrate and wherein the polymerizable promoter comprises at
least one polymerizable prepolymer having at least one ethylenically unsaturated group
and at least one carboxylic acid group.
53. A kit for priming for bonding or sealing a dental or biological substrate with a
primer comprising:
(a) a substrate conditioner; and
(b) a primer comprising a natural resin, a polymerizable resin, and a
polymerization initiator.
54. A premixed primer for sealing or priming for bonding a dental substrate
or a biological substrate, the stable premixed primer comprising:
a polymerization initiator;
a polymerizable resin; and
a polymerizable promoter characterized as being capable of being polymerized in
situ by initiation of the polymerization initiator after the primer is placed in contact with
the substrate. wherein the polymerizable promoter is selected from the group consisting
of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid,
and wherein the polymerizable initiator, polymerizable resin and the polymerizable

32/2
promoter once mixed thereafter form a stable premixed primer ready for storage and
subsequent application directly to the substrate without additional mixing.
55. A kit as defined in claims 51, 52 or 53, wherein the substrate conditioner is an acid
etching solution.
56. A method for preparing a stable premixed primer for sealing or priming for
bonding a dental or biological substrate, comprising the step of mixing a polymerization initiator,
a polymerizable resin, and a polymerization promoter to form a stable premixed primer ready for
storage and subsequent application directly to the substrate without additional mixing, wherein
the polymerizable promoter is characterized as being capable of being polymerized in situ by
initiation of the polymerization initiator after the stable premixed primer is applied to the substrate
and wherein the polymerizable promoter is selected from the group consisting, of methacrylic acid,
4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid.
57. A method for priming for bonding or sealing a dental or biological substrate with
a stable premixed primer comprising the steps of:
applying a stable premixed primer to the substrate, the stable premixed primer
comprising a polymerization initiator, a polymerizable resin and a polymerizable promoter,
wherein the polymerizable promoter is characterized as being capable of being
polymerized in situ by initiation of the polymerization initiator after the stable premixed
primer is applied to the substrate, wherein the polymerizable promoter is selected from the
group consisting of methacrylic acid, 4-pentenoic acid, 6-heptenoic acid and
2,2-dimethyl-4-pentenoic acid, and wherein the premixed stable primer is characterized after being
premixed as being ready for storage and subsequent application directly to a substrate
without additional mixing; and
initiating the polymerization of the polymerizable resin and the polymerizable
promoter.

32/3
58. A method for preparing a primer for sealing or priming for bonding a dental or
biological substrate, comprising the step of mixing a polymerization initiator, a natural resin, and
a polymerization promoter to form a primer, wherein the polymerizable promoter is characterized
as being capable of being polymerized in situ by initiation of the polymerization initiator after the
primer is applied to the substrate and wherein the polymerizable promoter comprises at least one
polymerizable prepolymer having at least one ethylenically unsaturated group and at least one
carboxylic acid group.
59. A method for priming for bonding or sealing a dental or biological substrate with
a primer comprising the steps of:
applying a primer to the substrate, the primer comprising a polymerization
initiator, a natural resin and a polymerizable promoter, wherein the polymerizable
promoter is characterized as being capable of being polymerized in situ by initiation of the
polymerization initiator after the primer is applied to the substrate and wherein the
polymerizable promoter comprises at least one polymerizable prepolymer having at least
one ethylenically unsaturated group and at least one carboxylic acid group; and
initiating the polymerization of the polymerizable promoter.
60. A kit for priming for bonding or sealing a dental or biological substrate with a
primer comprising:
(a) a substrate conditioner; and
(b) a stable premixed primer comprising a polymerization initiator, a
polymerizable resin, a polymerizable promoter, wherein the polymerizable promoter is
characterized as being capable of being polymerized in situ by initiation of thepolymerization initiator after the stable premixed primer is applied to the substrate,
wherein the polymerizable promoter is selected from the group consisting of methacrylic
acid, 4-pentenoic acid, 6-heptenoic acid and 2,2-dimethyl-4-pentenoic acid and wherein
the polymerizable initiator, polymerizable resin and the polymerizable promoter once
mixed thereafter form a stable premixed primer ready for storage and subsequent
application directly to the substrate without additional mixing.

32/4
61, A kit as defined in claim 115, wherein the substrate conditioner is a grit blaster.
62. A kit as defined in claim 115, wherein the substrate conditioner is an acid etching
solution.
63. A kit for priming for bonding or sealing a dental or biological substrate with a
primer comprising:
(a) a substrate conditioner; and
(b) a primer comprising a polymerization initiator, a natural resin and a
polymerizable promoter, wherein the polymerizable promoter is characterized as being
capable of being polymerized in situ by initiation of the polymerization initiator after the
primer is applied to the substrate and wherein the polymerizable promoter comprises at
least one polymerizable prepolymer having at least one ethylenically unsaturated group
and at least one carboxylic acid group.
64. A kit as defined in claim 118, wherein the substrate conditioner is a grit blaster.
65. A kit as defined in claim 118, wherein the substrate conditioner is an acid etching
solution.

Description

CA 02217490 1997-10-03
W O 96/31559 PCTrUS~
COMPOSITION FOR PRIMING DENTAL AND BIOLOGICAL S~i~STRATES
.
Bal~k~round of the Invention
1. The Field of the Invention
This invention relates to improved compositions and methods for priming or sealing dental
substrates and biological substrates, particularly exposed dentinal tooth surfaces, in order to
obtain strong adhesion when followed by an app. up- iate material such as a resinous material or
glass ionomer cement. More specifically, the invention relates to improved compositions and
procedures for applying an app.oxi-..ately pH neutral dentin primer requiring no mixing by the
applicator as it is a highly stable one component primer system.
2. The Prior State of the Art
Resinous materials are widely used for a variety of dental uses, including cavity filling,
cosmetic ~nh~nc~m~.nt and the c~ment~tion or adhesion of resinous and non-resinous materials.
Because tooth enarnel is comprised mostly of calcified minerals, it is very hard and can be
physically cleaned and chemically etched (conditioned) in preparation for bonding with resinous
materials. Once dried by air, and/or using a drying agent, the enamel tends to remain relatively
dry. Af'~er the enamel has dried, hydrophobic type resins can be bonded on to the enamel. This
bond between dried enamel and hydrophobic resins as well as the process of obtaining such
bonds are possible primarily due to the inorganic mineral content of enamel which is very high
compared to that of dentin.
In sharp contrast to the process involved in bonding resinous materials to enamel, it is
much more difficult to obtain completely dry dentin by using a drying agent and/or air drying
te~.hn~ -es This is because dentin contains thousands of dentin tubules which radiate outward
from the pulp ofthe tooth and which contain pulp fiuid under pressure. A cross-section of dentin
culll~ls approximately 35,000 dentin tubules per square millimeter, which can ooze fluids from
the pulp after the dentin surface is cut or drilled and the smear layer has been altered or removed.
Cutting or drilling the dentin creates a "smear layer," which is a semi-~tt~checl, weakened
layer of dentin. Tests have shown that it is difficult to obtain strong bonds between resinous

CA 02217490 1997-10-03
W O96/31559 PCTrU~v !~
materials and dentin unless the smear layer has been subst~nti~11y removed. This is usually
accomplished by the use of aqueous acid solutions or r.hrl~in~ agents.
Another ob:iL~lc to ob~i~ , strong bonds between resinous materials and dentin is that
dentin is relatively soft and less durable than enamel. While enamel has a mineral content over
97% comprising mainly calcium hydroxyapatite, phosphates, etc, dentin comprises only about
45% mineral material--the other 55% being a fibrous protein matrix and water. Dentin,
therefore, has a hardness, strength and chemical composition more similar to bone tissue.
Not only is enamel easier to dry and to keep dry compared to dentin, it can be more
predictably etched in order to yield a superior bonding surface. Chemical etching, typically by
means of a moderately strong acid (such as 30-40% aqueous phosphoric acid) creates
microscopic irregularities and undercuts into which a resinous material can enter, thereby
providing a strong, reliable bond to the etched enamel.
The first attempts to improve dentin bonding involved trying to implant resinous "tags"
within the cores of the dentin tubules. This mech~ni.cm, developed by Japanese scientists in the
1970's, posh-l~ted that resinous materials could form reliable bonds via these tags. However, due
to the relatively small cross-sectional area of the dentin tubules compared to the dentin surface,
and because resins shrink upon polymerizing, and due to the pulp fluid within the dentinal
tubules, the resinous tags did not adhere well to the dentin. Hence, this method did not result
in acceptably strong and durable bonding to dentin.
During this time and after, the theory among dentists and dental researchers in the U.S.
was that it was not desirable to remove the entire smear layer, although it later became
understood that any resulting bonds could be no stronger than the bond of the smear layer to the
dentin.
Later generation formulations generally reflect the teachings of Rafael L. Bowen and
others. These achieve bond strengths of around 14-20 MPa. A number of patents generally
reflect this later school of thought, inrlul1ing, e.~., U.S. Patent No. 4,588,756 to Bowen; U.S.
Patent No. 4,659,751 to Bowen; and U.S. Patent No. 4,964,911 to Ibsen et al. Bowen '756
teaches a three step process which includ.oc the following steps: first, applying a polyprotic acid;
second, applying a solvent co..~ g at least one compound selected from the group consisting
of N-phenylglycine, the adduct of N(p-tolyl)glycine, and glycidyl methacrylate (hereinafter
'~G-GMA"), and the addition reaction product of N-phenylglycine and glycidyl methacrylate
(hereinafter "NPG-GMA"); and third, applying a solution containing at least one compound

, CA 02217490 1997-10-03
W O96/315~9 PCT~U~ r-~-
selected from the group con.ci~tin~ of the addition reaction product of pyromellitic acid dian-
hydride and two hydroxyethyl methacrylate (he,~lel "PMDM"), the addition reaction product
of 3,3',4,4'-bel.~ophenoneletracarboxylic dianhydride and 2-hydroxyethylmeth~crylate
(hereinafter "BTDA-HEMA") and 4-meth~cryloxyethyltrimelliticanhydride (hereinafter "4-
META").
Bowen i75 1 teaches a two step process which in~lu(lçs the following steps: first, applying
an aqueous acid solution incl~ldin~ strong acids, acids cont~ining polyvalent cations, and acids
which form p~ec~ ales with c~lsi~lm, and a compound selected from the group consisting of N-
phenylglycine, NTG-GMA, and NPG-GMA; and second, applying a solution cont~ining either
PMDM, BTDA-HEMA, or 4-META.
Ibsen '911 teaches a similar three step process which includes the following steps: first,
applying an acidic solution containing a variety of strong and polyprotic acids; second, applying
a solvent co..l~ g a variety of different resins or amino acids; and third, applying a solution of
PMDM.
A number ofthese later generation commercial dentin bonding agents are sold, including
AD Bond II (m~mlf~ctllred by Bisco Dental Products), Prisma Universal Bond III (m~nuf~ctllred
by Dentaply), Tenure (m~nllf~ct~red by Den-Mat Co.), and Multi-Purpose (m~nllf~ctured by
3M).
Dentin primers are now available which do not require mixing, such as, Opti-Bond from
Kerr and Prime and Bond from Caulk Dentsply. Although, such primers and/or bonding agents
can be more quickly used than primers requiring mixing at the time of application, there are
disadvantages which ~ni~ e their usçfi-ln~ss. One of the primary disadvantages of these
primers is related to the need for mlll . Ie coats. The ~ffiriçncy gained by using premixed primers
is lost by the need for multiple coats to obtain adequate coverage and polymerization. The
economic ~IsPfi-lness of the primers is also limited since the shelf life of such dentin primers is
typically very short despite the claims of the m~nuf~c.turers It is well known in the industry
among prominent lecturers and clinicians that most of the primers have a significantly shorter
shelf life than claimed by the m~n~lf~chlrers. Additional problems may result from the highly
~ acidic nature of such primers. The low pH is potentially harmful since the polymerized primer
may leach and since a residual portion of the primer is typically not polymerized thereby
rP.m~ining acidic and in close contact with the dentin. A residual unpolymerized portion could
also potentially cause continued degradation to the rçm~ining tooth structure. Low ph may also

CA 02217490 1997-10-03
W O96/31559 PCT~U~
cause potentially high tooth sensitivity and may even cause painful injury if the acidic primer
comes into contact with the pulp of a tooth underlying the exposed dentin.
Additionally conventional primers when applied to a biological substrate as a sealant
before ap~olic~lion of c~ ion materials such as glass ionomer cement, polycarboxylates and
the like usually to interfere with the ability of c~m~nt~ to bond. Inadequate bonding strengths
usually result when a conventional primer is applied to a metal, enamel, porcelain or composite
and then followed by a bonding resin.
In view of the fo,~goi"g, it would be an advancement in the dental art to provide
compositions and methods for more efficiently obtaining stronger, more predictable bonds
between dentin and subsequently placed resinous materials. It will be appreciated that it would
also be a significant improvement over the prior art to provide dental compositions having a long
shelf life which would result in dependable bonds over time during storage and usage
Further, it would be a significant improvement if the dentin bonding primer was stable as
one component and more stable than all types of existing dentin primers.
It would be an improvement over the prior art to provide compositions and methods for
sealing a biological substrate without interfering with the bond achieved with a material which
is thereafter applied such as glass ionomer cement, carboxylate cements or the like.
Further, it would be a significant advancement in the dental art to provide composition
and methods for a single component primer which has an approximately neutral pH level.
Finally, it would be an important advancement if such compositions and methods could
provide significant bonding strengths to an appropriately conditioned enamel, porcelain, metal
or composite surface(s) when followed by an appl op, i~e resin.
Such compositions and procedures for achieving these results are set forth and claimed
herein.
Summary of the Invention
The present invention provides compositions and methods for priming or sealing dentin
of a tooth to prepare the dentin for bonding with an appropriate resinous material. Additionally,
the primer can be used with other dental or biological substrates such as enamel, porcelain or
composite crowns, and metal crowns or fillings. The resulting bonds have been shown to be
more durable over time. The compositions and methods of the present invention also allow for

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.
W O 96/31S59 PCTrUS3"~ -2
greater convenience beç~-se they remain stable until needed by the dentist over a significantly
long shelf life.
In a ~lèrelled embodiment, the dentin~l smear layer is first removed by conditioning the
dentin surface with 35% pho~ ;c acid, after which the dentin is washed with water to remove
the aqueous acid and dissolved dentin minerals. Although 35% aqueous phosphoric acid is
prerelled~ concentration ranging from 10% to 40% works well. In addition, other dilute acids
or chelators also work well. After the conditioning treatment, surface water is removed by air.
The dentin primer of the present invention is applied to the dentin after apl)l Opl iate water
removal. The dentin primer is applied to seal the dentinal tubules and prepare the dentin surface
for bonding with an appropriate resinous material.
The dentin primer comprises at least one polymerizable component and at least one
polymerization initiator. In one embodiment of the present invention, the dentin primer
COIII~ul ises a mixture of a polylllt;l i~lion initiator, such as camphoroquinone, and a polymerizable
promoter, such as methacrylic acid. Polymerizable promoters within the scope of the present
invention have at least one ethylenically unsaturated group and at least one carboxylic acid group.
The dentin primer may further comprise a volatile solvent such as ethanol, a natural resin such
as C~n~1i,~.n balsam, or a pol~llleli~ble resin such as HEMA. In another embodiment, the dentin
primer is formed from a mixture of a polStlllel~lion initiator, a natural resin and a polymerizable
resin,. The plerelled embodiment of the dentin primer comprises methacrylic acid, HEMA,
C,~.n~ n balsam, ethanol and camphoroquinone.
An advantage of the present invention is that the dentin primer of the present invention
is stable over time.
Although, patents may claim high bond strengths, hypothetical bond strengths obtained
by applying the prior art bonding agents under ideal conditions are of little worth if the exigencies
and difficulties of actual dental work make it impossible to repeat the process under actual
contlitions encountered by the dentist or if the shelf life is so short that testing conditions using
fresh material are not COlllp~u ~ble to the time implic~tiQns of how they are used in a typical dental
office.
- In addition to the above the benefits, the one component primer system of the present
invention requires no mixing by the applicator. This one component primer system has an
appl~ ely neutral pH level and is adequately integrated into the conditioned dentin with one
application.

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Yet another advantage ofthe present invention is ability of the compositions to be applied
as a sealant to a biological substrate without decreasing the bond strength of a material applied
Ll,e ~ler such as glass ionomer cement or polycarboxylate cement. The present invention also
yields atlequ~te bonding strengths when applied to an app,op,ia~ely conditioned enamel,
porcelain, metal or composite and then followed by a bonding resin.
Detailed Description of the Preferred Embodiments
The present invention relates to compositions and methods for priming or sealing a
substrate in a living body incl~ltiing prosthetic substrates to be incorporated into the living body,
such as a dental or biological substrate, in order to obtain strong adhesion when followed by an
appropriate material such as a resinous material or glass ionomer cement. The term "dental
substrate" as used in the specific~tion and the appended claims is defined to include tooth enamel,
dentin, other structures of a tooth, metal crowns or fillings, porcelain crowns, composite fillings
or crowns, other dental prosthesis and other materials related to the repair and reconditioning
ofteeth. The term "biological substrate" as used in the specification and the appended claims is
defined as an organic or inorganic body part of a living organism. Examples of biological
substrates include but are not limited to bone, fingernails and also some dental substrates such
as enamel and dentin. The present invention has been developed particularly for use in priming
dentin for bonding or for use in sealing dentin, however, one skilled in the art can use the
te~chinge as applied to dentin for use in priming for bonding or sealing other substrates in a living
body in addition to dentin, particularly dental and biological substrates.
The dental and biological sul~L,~es can also be conditioned before the primer composition
is applied, although, it is not always necessary to condition the substrate. Conditioning dental
and biological substrates, such as dentin and enamel, generally involves application of an acid
such as phosphoric acid. Porcelain is also typically conditioned with an acid or grit blasting
treatment, hydrofluoric acid is particularly effective. Metals are typically conditioned by grit
blasting. The present invention inçlndes a kit comprising a substrate conditioner such as an
aqueous acid solution, a primer and an applop, iate bonding resin.
The present invention is particularly useful for priming exposed dentinal tooth surfaces.
After the primer has been applied to the dentin, an appropriate resinous material can be bonded
to the primer. Additionally, the present invention can be used to seal dentin before a cement is
applied such as glass ionomer cement, polycarboxylate cements (polyacrylic acid formulations)
and the like without negatively effecting the bond formed by the cement. An increase in bond

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stren~,th results from prim~ng such a surface before applying the glass ionomer c~m~nt which is
a Sl~ lg result. It is s l,l"i..ing that the bond is ~ ene~ since conventional primers tend
~ to interfere with bonds formed by glass ionomer c~.mente to dentin.Dentin colllains an enormous number of dentin tubules that radiate outwardly from the
pulp chamber. These d~ntin~l tubules are filled with a fluid which is contiguous with the pulp
chamber. Although the drilling and cutting of enamel is relatively painless, fluid movement
through the dentin~l tubules can act like nerves and can induce pain.
Once the dentin is cut, internal pressure within the pulp chamber can cause the fluid within
the dentinal tubules to flow out ofthe tubules and onto the dentinal surface. This has created one
of the major obstacles to obtaining strong bonds to dentin. The cutting of dentin l,y means of
a high speed drill or other cutting devices, as are typically employed by dentists to clear away
tooth decay and shape dimensions for the I c~.Lol ~lion, causes the formation of a weakened, semi-
attached layer which remains over the dentin called the smear layer. The smear layer has been
a major obstacle to obtaining strong bonds between resinous materials and dentin.
In addition, mucous-like fluid from the pulp chamber oozes through the dentin tubules and
deposits itself on the smear layer and is not easily dried. Therefore, it is advantageous to remove
and/or alter the entire smear layer. Then, before the dental material is applied, it is important to
seal the dentin tubules to provide a bonding substrate and to prevent fluid movement in the dentin
tubules thus alleviating sensitivity.
A preferred method entails first contacting the dentin surface with an aqueous acid
solution for about 20 seconds in order to remove subst~nti~lly all of the smear layer, but without
d~m~ing the dentin itself. It has been found that aqueous phosphoric acid works well in
conditioning the dentin. Any conventional conditioner can be used within the scope of the
present invention to condition the dentin inc.l~ling acidic solutions such as aqueous citric acid,
nitric acid, and other acids, as well as other known dentin conditioners inclulling chelators.
The phnsphoric acid solution within the scope of the present invention will typically have
a concentration within the range from between about 10% to about 40% (weight to volume),
with a concentration of about 35% being the most preferable A phosphoric acid solution having
a concentration of 35% (weight to volume) is available from Ultradent Products, Inc. in Salt
Lake City, Utah, under the trademark Ultraetch~3). After the smear layer is removed by the acid
solution, any excess acid is removed by flllshing the etched dentin with water.

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Once the smear layer has been s~ s~ lly removed, the second step entails removing any
excess moisture from the dentin surface. This is preferably performed by means of air blowing
or use of absorbent materials.
After the excess water has been removed from the dentin, the third step involves applying
the dentin primer to prepare the dentin surface for bonding. This is accomplished by applying
the prc""xed bonding agent of the present invention. After the dentin primer is applied, the
application is blown with clean air to thin the primer and/or dry solvent from the primer.
Appropriate resinous materials can be applied to the dentin after polymerization has occurred.
An appropriate resin material is applied to the dentin after polymerization of the primer.
A~plulJlial~ resins will usually include HEMA~ Bis-GMA, urethane dimethacrylate ("UDMA"),
TEGDMA or a combination of these.
The primer of the present invention comprises at least one polymerization initiator and
at least one polymerizable component. In one embodiment of the present invention, the
polymerizable component is a polymerizable promoter. The term "polymerizable promoter" as
used in the specification and the appended claims refers to a polymerizable monomer or
prepolymer having at least one ethylenically unsaturated group and at least one carboxylic acid
group, the polymerizable ~- ulllolt;- is characterized as being capable of being polymerized in situ
by means of the polymerization initiator after the polymerizable promoter is placed in contact
with the substrate.
The polymerizable promoter is preferably included in the primer in an amount in a range
from about 0.05% to about 99.95% by weight of the primer. The polymerizable promoter is
more preferably in~ ded in an amount in a range from about 0.5% to about 50% by weight of
the primer and most preferably in an amount in a range from about 0.75% to about 30% by
weight of the primer.
The preferred polymerizable promoter is methacrylic acid which is also known as 2-
methyl-2-propenoic acid. Other polymerizable promoters within the scope of the present
invention typically have the following formula:
R O
I ~
C=C - C - OH
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an unsaturated
aliphatic radical, a halogen or a CN radical.

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itiQn~lly, pol~""~li~ble promoters within the scope ofthe present invention can also
have the following formula:
R O
C=C - Rl - C - OH
wherein R is a hydrogen atom, a methyl group, a saturated aliphatic radical, an unsaturated
aliphatic radical, a halogen or a CN radical; and wherein R, is at least one oxygen atom, a
saturated ~lirh~tic radical, a saturated aliphatic radical interrupted by at least one oxygen atom,
an unsaturated aliphatic radical, an unsaturated aliphatic radical interrupted by at least one
oxygen atom, a homocyclic radical, a heterocyclic radical, a polymerizable moiety, or an aryl
radical having four to six carbon atoms and a valency of n+ I with n being an integer of at least
6. Such polymerizable promoters include but are not limited to 4-pentenoic acid, 6-heptenoic
acid and 2,2-dimethyl-4-pentenoic acid.
The polymerization initiator is selected from the group consisting of photoinitiators and
fh~.mic~l initiators. Photoinitiators include, but are not limited to, a-diketones with or without
tertiary amines, such as camphoroquinone, dimethylamino ethylmeth~crylate, and the like.
PholoilliLi~lors are the plc~r~ d polymerization initiators and camphoroquinone is the prerelled
pho~oiniLia~ol-. Chemical iniLia~ol ~ may also be used in the primer either alone or as incorporated
into the app~ iale bonding resin to follow. The polymerization initiator is preferably included
in the primer in an amount in a range from about 0.01% to about 2% by weight ofthe primer.
The polymerization initiator is more preferably in~.luded in the primer in an amount in a range
from about 0.03% to about 1.5% by weight of the primer, and most preferably included in the
primer in an amount in a range from about 0.05% to about 1% by weight ofthe primer.
The primer may further comprise polymerizable resins. The term "polymerizable resin"
as used in the specification and the appended claims refers to a either a hydrophilic polymerizable
compound with at least one hydroxyl group, a hydrophobic polymerizable alkyl, or a
polymerizable compound having at least one hydrophobic moiety and at least one hydrophilic
moiety. Polymerizable resins within the scope of the present invention include hydroxyalkyl
methacrylates, hydroxyalkyl acrylates, alkyl meth~crylates, or alkyl acrylates. Particularly useful
examples of the above polymerizable resins within the scope of the invention include 2-
hydroxyethyl methacrylate (HEMA), bisphenol-A-glycidyl methacrylate, glycerol dimethacrylate,
methyl acrylate, triethylene glycol 11im~th~crylate and the like. It is preferable to use hydrophilic
resins such as HEMA, as the dentin colll;~lls si~ific~nt moisture, which results in better adhesion

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between the dentin and the primer. Polymerizable resins within the scope of the present
invention may also have at least one phosphate group and/or at least one amine group.
The pol~ e resin is preferably inrll-ded in the primer in an amount in a range from
about 0.05% to about 95% by weight of the primer. The polymerizable resin is more preferably
S inrl~ldecl in the primer in an amount in a range from about 0.5% to about 80% by weight of the
primer and most p-c;r~-~bly inclllded in the primer in an amount in a range from about 0.75% to
about 70% by weight of the primer.
The primer may further comprise a solvent selected from the group consisting of a
hydrophilic hydrocarbons, hydrophobic hydrocarbons, and water. The solvent imparts a
desirable viscosity to the primer, which may increase the ability of the primer to flow into the
intim~te spaces afforded by selectively removing mineral components of dentin as per the
conditioning (etching or chelating step). The solvent improves the ability of dentin bonding
promoter(s) to make more intim~te contact and impregnate into the conditioned dentin surface.
The hydrophilic solvents are particularly useful since normal dentin is naturally moist.
Examples of suitable solvents include ethanol and acetone. The solvent is preferably
inc1. ~de~i in the primer in an arnount in a range from about 0.05% to about 95% by weight of the
primer. The solvent is more preferably inclllded in the primer in an amount in a range from about
0.5% to about 80% by weight of the primer, and most preferably included in the primer in an
amount in a range from about 0.75% to about 50% by weight ofthe primer. The pr~rell~:d
solvent is ethanol. The solvent may be used in a primer comprising only a polymerizable
pl.~ ol~l and a polylll~li~lion initiator. The solvent may also be combined with a polymerizable
promoter, a polymerization initiator, and a polymerizable resin.
A natural resin may also be inclucled in the primer. The term "natural resin" as used in the
.cpec.ific~tion and the appended claims includt-s resins, distillates, saps, oils, bal.~m~ or gums that
come from natural sources such as trees, shrubs, plants or seeds. Any natural resin is within the
scope ofthe present invention particularly those selected from the group consisting of ('~n~ n
balsarn, sandarac, mastic, ponti~n~k, copal, rosin, manilla, peruvian, benzoin, elemi, opopanax,
olih~nl-m, styrax, benzoin siam, tolu, tall, pine and the like. Mixtures of various natural resins can
also be incorporated into the primer. Natural resins within the scope of the present invention
include natural resins which are either polymerizable or non-polymerizable. Additionally, natural
resins within the scope of the present invention either enhance the bond strength between a
substrate primed with a primer c.~n~;.li..g such natural resins.and a subsequently applied bonding

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11
material or do not in a ~i~nifir~nt manner adversely effect the bond strength. It is within the
scope of the present invention to co,llbille any of these natural resins with any conventional
- dentin primer bonding systems.
One of ordinary skill in the art would not expect to obtain a high bond strength between
a polymerizable dental resin and a primer co.~ g a natural resin as it has been well known
since the advent of polymerizable dental materials that such materials adjacent to natural resins,
such as copal rosin or copalite varnish, do not polymerize or harden. It is also known that
Eugenol, which is derived from oil of cloves, can adversely effect polymerization of resinous
dental materials.
Temporary cements are useful to retain a temporary crown in place. Temporc,ry cements
are weak so they can easily be removed when the permanent crown is ready fo permanent
p!~ rm.ont Eugenol in tempo,~ y cements can prevent complete polymerization of polymerizable
dental resins such as methyl methacrylate, Bis-GMA and the like. Additionally, plastic crowns
which have already been polymerized and are then placed in contact with a temporary cement
cont~inin~ Eugenol are softened by the Eugenol. It is also known that the Eugenol containing
temporary c~.ments must be completely removed from the tooth preparation before a
polymerizable dental resin is applied as residual amounts of the Eugenol have an adverse effect
on the ability of a polymerizable dental resin to polymerize and bond. Surprisingly, primers of
the present invention are not as sensitive to residual Eugenol. It has been found that residual
Eugenol does not adversely effect the bond strength when an appropriate resin material is applied
after the dentin has been primed with a primer of the present invention.
In summary, the adverse effect of Eugenol and copal rosin on polymerizable dental resins
would not suggest that a .cignifir.~nt bond would result between a polymerizable dental resin and
dentin primed with a primer collt;~ a natural resin or that the polymerizable dental resin
would effectively polymerize. It is also surprising that polymerization is effectively achieved of
polymerizable components intermixed with natural resins in the polymerizable primer of the
present invention. Additionally, since the exact small quantity chemical content of each natural
resins is not known, one of oldinal y skill in the art would not expect to obtain a highly stable
system by inco~ ~.o, ~ing such a natural resin in a polymerizable composition.
The natural resin is preferably included in the primer in an amount in a range from about
0.05% to about 55% by weight of the primer. The natural resin is more preferably included in
the primer in an amount in a range from about 0.5% to about 3 5% by weight of the primer, and

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12
most p,~f~ bly in~ ded in the primer in an amount in a range from about 0.75% to about 20%
by weight of the primer.
It is within the scope of the present invention to form primers comprising at least one
poly",~;li~ble prc,llloler, at least one natural resin, at least one solvent and at least one
polymerization initiator. It is also within the scope of the present invention to form primers
comprising at least one polymerizable promoter, at least one natural resin, at least one
polymerizable resin and at least one polymerization initiator.
The pler~l,ed embodiment comprises at least one polymerizable promoter, at least one
natural resin, at least one hydrophilic polymerizable resin, at least one solvent and at least one
polymerization photoinitiator and a chemical initiator. In some cases it is desirable to include a
chemical initiator since in all circumstances light cannot appropriately reach the application site
to cause complete polymerization or cannot address polymerization in a desired direction. In the
most preferred embodiment the polymerizable promoter is methacrylic acid, the natural resin is
C~n~ n balsam, the polymerizable resin is 2-hydroxyethyl methacrylate (HEMA), the solvent
lS is ethanol and the polymerization initiator is camphoroquinone. By weight of the primer, the
composition ofthe most p,~rt:.,ed embodiment comprises about 6% methacrylic acid; about 15%
C~n~ n balsam, about 53.3% 2-hydroxyethyl methacrylate, about 25% ethanol and about 0.7%
camphoroquinone .
In two alternative embodirnpnt~ the polymerizable component is a polymerizable resin and
not a pol~ll,t:,i~le promoter. In one of the embodiments, the primer comprises a natural resin,
a polymerizable resin and a polymerization initiator. In the other alternative embodiment, the
primer coln~, ises a natural resin, a polymerizable resin, a solvent and a polymerization initiator.
It is currently believed that the components of.the dentin bonding promoter havehydrophilic moieties, particularly the carboxylic acid groups of the polymerizable promoters,
which tend to interact with the hydrophilic surface of the dentin, while the more hydrophobic
moieties tend to orient themselves outward, creating a much more hydrophobic surface with
which the resinous materials can interact. Regardless of the actual meçh~ni.~m involved, greatly
improved bond strengths have been demonstrated. In fact, the bond strengths are usually
~llung~ than the dentin itself, which results in test fractures occurring within the dentin instead
ofthe bond between the dentin and resinous material.
The dentin primers ofthe present invention yield bond strengths between about 15-35
MPa depending on the protocol of individual laboratories. In addition to superior bond strengths

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13
co.l.paled to dentin bonding agents available on the market today, the dentin primers of the
present invention have a relatively long shelf life and do not require multiple cOdlillgS.
Examples of the Preferred Embodiments
- 5 Exarnples are provided ofthe present invention in order to compare the properties of the
compositions by varying the content of the components of the dentin primer. Examples I-13
describe dentin primers which were prepared in accol dance with the present invention. Examples
14-18 d~s~;lil,ed dentin primers which can be hypothetical prepared based on actual mix designs
in accc,.d~ce with the present invention. While examples 14-18 are hypothetical in nature, they
are based upon actual mix designs that have been tested or co"L~",~lated and are presented in this
forrn in order to more completely illustrate the nature of the invention.
Example I
A dentin primer was formed from the following components:
ComponentPercent by Wei~ht of the Mixture
Methacrylic Acid6.0
Can~ n Balsam 15.0
HEMA 53 3
Ethanol 25.0
Camphoroquinone0 . 7
Dentin was etched with a phosphoric acid solution having a concentration of about 35%.
The etched dentin was flushed away with water and then the dentin was dried by air.
A~er the dentin primer was prepared, it was placed in a syringe assembly and delivered
onto the dentin which had been etched, rinsed and dried. The viscosity of the dentin primer was
low enough that the dentin primer sufficiently flowed into the micro spaces of the conditioned
dentin. Polymerization was achieved by exposing the primer to light. The dentin primer had a
pH which was almost neutral. The dentin primer adequately adhered to the tooth surface where
it was applied. A resin material was applied and the strength of the resulting bond was most
~ignifi~;~nt as it was very high. The process was repeated and it was found that the process was

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14
~epea~l~'e in appro~i",alely equal time periods and that the bond strengths were approximately
equal.
Example 2
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Mixture
Methacrylic Acid 6.0
C~n~ n Balsam 15.0
HEMA 53.3
Bisphenol-A-glycidyl methacrylate 5 .0
Ethanol 20.0
Camphoroquinone 0.7
Dentin was etched with a phosphoric acid solution having a concentration of about 35%.
The etched dentin was flushed away with water and then the dentin was dried by air.
After the dentin primer was prepared, it was placed in a syringe assembly and delivered
onto the dentin which had been etched, rinsed and dried. The viscosity of the dentin primer was
very similar to the viscosity in Example 1 and was low enough that the dentin primer sufficiently
flowed into the micro spaces of the conditioned dentin. Polymerization was achieved by
exposing the primer to light. The dentin primer had a pH which was almost neutral. The dentin
primer adhered to the tooth surface where it was applied and formed a bond with a resin material
applied onto the primer which had a strength approximately equal to the bond strengths achieved
in Example I when resin material was applied to the primer.

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Example 3
A dentin primer was formed from the following components:
-
Ccil-lponelll Percent by Wei~ht of the Primer
S Methacrylic acid 6
HEMA 52.6
Can~ n balsam 15
Ethanol 25.4
Benzoyl Peroxide
The composition of this primer behaved similarly to the composition of the primer
prepared in Example 1. The polymerization initiator in this composition was a chemical initiator.
The chemical initiator, benzoyl peroxide, adequately initiated polymerization when contacted
with an aromatic amine accelerator in the resinous material.
Example 4
A dentin primer was formed from the following components:
Component Percent by Weight of the Primer
Methacrylic acid 7
Canadian balsam 15
HEMA 47.5
Ethanol 25
Acetone 4
Camphoroquinone 0.6
2,2' p-tolyimino diethanol 0.9
The coll-po~i~ion ofthis primer was nearly identiç~l to composition of the primer prepared
in F.Y~mple 1, except that acetone was also inrluclecl as a solvent and polymerization was initiated
by a pholo;.~ ol and a rh~.m:-~1 initiator. The use of ethanol and acetone together as a solvent
was less effective than using ethanol alone. The chemical initiator, 2,2' p-tolyimino diethanol,

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16
adequately initi~ted polymerization when contacted with a free radical initiator in the resinous
material.
Example S
A dentin primer was formed from the following components:
s
Component Percent by Wei~ht of the Primer
Methacrylic acid 0.5
HEMA 62.9
C~n~ n balsam 15
Ethanol 20.4
Camphoroquinone 0. 7
Benzoyl peroxide 0.5
Polymerization was adequately initiated by the combined use of a photoinitiator and a
r~hem:csll initiator. The dentin was adequately covered and the bond strength was significant but
weaker than the bond strength achieved with the composition in Example 1.
Example 6
A dentin primer was formed from the following components:
Component Percent by Wei~;ht of the Primer
Methacrylic acid 6.4
HEMA 52.9
Ethanol 40
Camphoroquinone 0.7
This dentin primer was prepared without any natural resins and a larger amount of solvent
than the dentin primer prepared in Example 1. The primer was easily covered with the primer
which had a lower viscosity than the primer in Example 1. The bond was significant but
somewhat weaker compared to the bond formed in Example 1.

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17
Example 7
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Primer
Methacrylic Acid 10.0
Ethanol 89.3
Camphoroquinone 0.7
The solvent content was very high and was prepared without any natural resins orpolymerizable resins. The primer easily flowed since it had a very low viscosity, however, more
drying was n~cec.c~ry than in Example 1. Signifiç~nt bond strengths were obtained after multiple
coats were applied.
Example 8
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Primer
-Methacrylic acid 6.4
HEMA 77.9
Sandaracresin 15
Camphoroquinone 0. 7
The viscosity of the dentin primer was much higher than in Example 1 as there was no
solvent and the HEMA content was much higher. More air blowing was necessary to spread and
thin the primer than was necessary in Example 1, however, the primer sufficiently infiltrated the
conditioned dentin. The bond strength was significant but not as high as in Example 1.

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18
Example 9
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Primer
HEMA 80
Mastic resin 19.5
Ca~"pholuquinone 0.5
The viscosity of the dentin primer was much higher than in Example 1 as there was no
solvent and the resin content was 99.5% ofthe primer. Much more air blowing was necessary
to spread and thin the primer than was necessary in Example 1, however, sufficient contact was
achieved between the primer and the dentin. The bond strength was significant but not as high
as in Example 1.
Example 10
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Primer
Methacrylic acid 2
~nEMA 76.8
Bisphenol-A-glycidyl methacrylate 3.9
Pontianak resin 16
Ethanol 5
Camphoroquinone 0. 8
Due to the low solvent content, the viscosity of the dentin primer was relatively high and
resulted in the need for more air blowing to adequately spread and thin the primer than was
n~ce.~ry in Example 1. The strength of the bond was significant but weaker than the bond
formed by the primer of Example 1.

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19
Example 1 1
A dentin primer was formed from the following cQmponents:
Component Percent by Wei~ht of the Primer
Methacrylic acid 3
HEMA 84. 1
Copal gum 12
Camphoroquinone 0.9
The viscosity ofthe dentin primer was much higher than in Example I as tr,ere was no
solvent, however, ~ignifiç~nt impregn~tion was achieved by the primer into the dentirn The bond
strength was quite significant.
Example 12
A dentin primer was formed from the following components:
Component Percent by Wei~ht of the Primer
Methacrylic acid 6
HEMA 52.6
Olib~n-lm resin 15.4
Ethanol 25
2,2' p-tolylimino diethanol
The viscosity of the dentin primer was very similar to the viscosity of the primer described
in Example 1. Polymerization was adequately achieved by the chemical initiator, 2,2' p-
tolylimino diethanol, but was not as effective as camphoroquinone. The bond had significant
strength but was weaker than in Example 1.

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Example 13
A dentin primer was formed from the following com~onents:
Component Percent by Weight of the Mixture
Methacrylic Acid 6.0
C~n~ n Balsam 15.0
Maleic Acid 0.3
HEMA 53 .0
Ethanor 25.0
Camphoroquinone 0. 7
The dentin primer had an acidic pH, however, the strength of the bond formed when a
resin material was applied was very near the level of the bond strengths achieved by the
composition in Example 1.
Example 14
A dentin primer is forrned from the following components:
Component Percent by Weight of the Primer
Methacrylic acid 2
HEMA 30
C~n~ n balsam 31
Ethanol 35.8
Camphoroquinone 1.2
A dentin primer prepared by the above composition would be expected to have a
~ignifir.~nt bond strength but weaker than the bond formed in Example 1. The primer would also
be expected to be slightly less viscous than the primer prepared in Example 1 which would not
valy the process.
Example 15
A dentin primer is formed from the following components: -

CA 02217490 1997-10-03
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21
ComponentPercent by Wei~ht of the Primer
Methacrylic acid 8
HEMA 91. 1
Camphoroquinone 0.9
A dentin primer p,~pa-t;d by the above composition would be expected to have a
~i nifiç~nt bond strength but lower than in Example 1. Additionally, the dentin primer would be
expected to be very viscous as no solvent is used and the ~MA content is very high. Much
more air blowing would be necessary to spread the relatively viscous mixture.
Example 16
A dentin primer is formed from the following components:
Component Percent bv Wei~ht of the Primer
Methacrylic acid 99.3
Camphoroquinone 0. 7
A dentin primer prepared by the above composition would be expected to have a
significant bond strength but weaker than the bond formed in Example 1. The viscosity would
be low since methacrylic acid has a low viscosity. The dentin primer formed in accordance with
the above composition would be expected to provide a bond strength having significant but less
than Example 1.
Example 17
A dentin primer is formed from the following components:
ComponentPercent by Wei~ht of the Primer
Methacrylic acid 9
Tolu balsam 19
Camphoroquinone 0.6
Ethanol 7 1.4

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22
A dentin primer prepared by the above composition would be expected to have a low
viscosity due to the high amount of solvent allowing the primer to easily cover the dentin,
however, mllltiple coats may be necessary to obtain significant bonding. Although, the bond
between a subsequ~ntly applied appropriate resin material and the primer would be expected to
be significant, it would also be expected to be l~wer than the bond formed in Example 1.
Example 18
A dentin primer is formed from the following components:
Component Percent bv Wei~ht ofthe Primer
E~EMA 1 3
Camphoroquinone 1.2
Ethanol 76.3
Manila resin 20
A dentin primer prepared by the above composition would be expected to have a very low
viscosity due to the high amount of solvent allowing the primer to easily cover the dentin,
however, multiple coats may be necessary to obtain significant bonding. Although, the bond
between a subsequ~ntly applied al)pl ~IJ, iate resin material and the primer would be expected to
be significant, it would also be expected to be lower than the bond formed in Example 1.
Sum marv
From the foregoing, it will be appreciated that the present invention provides novel
compositions for a dentin primer and methods for priming dentin.
In particular, the present invention provides dental compositions and methods for more
efficiently obtaining stronger, more predictable bonds between dentin and subsequently placed
resinous materials. It will also be appreciated that an object of the present invention is to provide
compositions having a long shelf life which would result in dependable bonds over time during
storage and usage.
The present invention also provides dental compositions and methods which are more
simple to use than in the prior art by providing a dentin primer which is stable as a one
component system and more stable than all types of existing dentin primers.

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23
The present invention fllrther provides compositions and methods for sealing a biological
substrate without i,l~e,rt ,i,-g with the bond achieved with a material which is thereafter applied
- such as glass ionomer cement or polycarboxylate cemPnt~
Further, the present invention provides compositions and methods for a single component
primer which has an appl ox i"~ately neutral pH level.
Finally, the present invention provides compositions and methods for obtaining significant
bonding strengths with an appropriately conditioned enamel, porcelain, metal, or composite
surface(s) when followed by an apl)rop,iate bonding resin.
The present invention may be embodied in other specific forms without departing from
its spirit or ç~enti~l characteristics. The described embodiments are to be considered in all
,e~ only as illustrated and not restrictive. The scope of the invention is, therefore, indicated
by the appended claims rather than by the foregoing description. All changes which come within
the meaning and range of equivalency of the claims are to be embraced within their scope.
What is claimed is: